Variation in the choanal structure of Recent turtles

1968 ◽  
Vol 46 (6) ◽  
pp. 1235-1263 ◽  
Author(s):  
Thomas S. Parsons
Keyword(s):  
Interspecific Differences ◽  
Specific Variation ◽  
Taxonomic Implications ◽  
Lateral Margins ◽  
Almost All

The choanal regions of all the living genera and almost all of the living forms of turtles are described, based on a sample of over 4000 specimens. In all families of cryptodires except the cheloniids and derrnochelyids there are usually ridges or flaps along the lateral margins of the choanae. In chelydrids, most kinosternids, some platystemids, some emydids, and some trionychids there is a papilla or bulge extending medially into the choana from this flap or ridge, and in dermatemydids, carettochelyids, and some trionychids there may be several or many such papillae, Cheloniids have one, or in Chelonia many, papillae along the lateral choanal margin. Other forms lack these papillae. Dermochelyids and pleurodires have no special structures along the lateral choanal margins. In almost all cases there is some and often there is considerable variation in these structures.The possible phylogenetic and taxonomic implications of the findings are discussed. In some groups such as the genera of emydids, the choanal structure may prove to be taxonomically useful, but in other cases it does not seem helpful. For example, in the trionychids, the intra-specific variation is so great that it largely obscures the interspecific differences.

scholarly journals An Exceptional Large Sample of the Early Miocene Ctenodactyline Rodent Sayimys Giganteus, Specific Variation and Taxonomic Implications

2019 ◽  
Vol 75 (3-4) ◽  
pp. 359-382
Author(s):  
Julian Hartman ◽  
Andrew A. van de Weerd ◽  
Hans de Bruijn ◽  
Wilma Wessels
Keyword(s):  
Saudi Arabia ◽  
Middle Miocene ◽  
Morphological Changes ◽  
Early Miocene ◽  
Dental Morphology ◽  
Tooth Position ◽  
Specific Variation ◽  
Nomina Dubia ◽  
Taxonomic Implications ◽  
Almost All

Abstract An assemblage of the early Miocene Sayimys giganteus (Ctenodactylinae, Rodentia) from its type locality Keseköy, and smaller assemblages of Yapıntı and Horlak (Anatolia, Turkey) are described. Almost all Sayimys species are known from small collections of isolated cheek teeth. The very large assemblage from Keseköy is of special interest, because it allows the study of the intra-specific variation of dental morphology: size, the morphological changes through wear and the criteria for recognition of the tooth position of molars. The results have been used to review the formally named Sayimys species and to evaluate the dental features used to define the species. The review of the early and middle Miocene succession of Sayimys in the Siwaliks (Pakistan) resulted in the resurrection of S. minor; S. baskini is considered to be a junior synonym of S. minor. S. sivalensis and S. obliquidens are nomina dubia, and restricted to their holotypes, S. hintoni n. sp. is established for mediumsized Sayimys from the Kamlial, lower Chinji and Manchar Formations and S. chinjiensis is resurrected for Sayimys from the upper Chinji and Nagri Formations. It is suggested that the middle Miocene species Sayimys intermedius and S. assarrarensis from Saudi Arabia are synonymous.

scholarly journals Distribution of Serotonergic Neurons in the Central Nervous System: A Peroxidase-Antiperoxidase Study with Anti-Serotonin Antibodies

1983 ◽  
Vol 31 (1A_suppl) ◽  
pp. 181-185 ◽  
Author(s):  
Y. Takeuchi ◽  
H. Kimura ◽  
T. Matsuura ◽  
T. Yonezawa ◽  
Y. Sano
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neuronal Somata ◽  
Immunohistochemical Technique ◽  
Interspecific Differences ◽  
System A ◽  
Highly Sensitive ◽  
Serotonin Antibodies ◽  
The Central Nervous System ◽  
Almost All

Distribution of serotonin (5-HT) neurons in the central nervous system (CNS) of various vertebrates was investigated with a highly sensitive immunohistochemical technique. Antibodies were raised in rabbits against an antigen prepared by coupling 5-HT to bovine thyroglobulin. 5-HT neurons were found to be distributed more widely and densely than has been heretofore described. Serotonergic neuronal somata are organized according to certain basic patterns, but there are interspecific differences with regard to the distribution of 5-HT fibers. The processes of 5-HT neurons form a dense plexus by ramification and anastomosis in almost all areas of the CNS, including the ventricular surfaces. In the light of our observations, Golgi's reticular theory may have to be revised.

Amino acids in the octocoralVeretillum cynomorium: the effect of seasonality and differences from scleractinian hexacorals

2012 ◽  
Vol 93 (4) ◽  
pp. 913-918 ◽  
Author(s):  
Miguel Baptista ◽  
Ana Luísa Maulvault ◽  
Katja Trübenbach ◽  
Luis Narciso ◽  
António Marques ◽  
...  
Keyword(s):  
Amino Acid ◽  
Principal Component ◽  
Dry Weight ◽  
Amino Acid Profile ◽  
Temporal Variations ◽  
Total Amino Acid ◽  
Interspecific Differences ◽  
Biochemical Studies ◽  
Almost All ◽  
First Time

The majority of biochemical studies in corals has been focused on the lipidic composition and little attention has been given to the amino acid profile of these invertebrates. The objectives of this work were to investigate, for the first time, the temporal variations in the total amino acid (AA) composition of an octocoral, namely the sea penVeretillum cynomorium, and to evaluate possible interspecific differences in AA profile between this octocoral and hexacorals. The quantitatively most important AAs inV. cynomoriumcolonies were: glutamic acid, varying from 3.92 to 5.94% dry weight (dw) and representing around 14–15% of total AA content; aspartic acid (3.34–4.99% dw; 11–12%); and glycine (2.87–4.57% dw; 9–12%). On the other hand, the minor AAs were methionine (0.41–0.73% dw; 1–2%) and histidine (0.54–0.76% dw; 2%). Almost all AAs showed the same significant seasonal variations, with the highest values in February, second highest in October and the lowest in June. Some AAs, namely lysine, phenylalanine and methionine did not follow this trend and showed the major peak in October. Most of the AA variations seemed to be linked to changes in food availability and/or gametogenesis. Principal component analysis clearly separated the octocoral from the group of hexacorals, mainly due to the higher percentages of arginine, tyrosine and glycine inV. cynomorium, and valine, serine, histidine, isoleucine and alanine in hexacorallia species. We speculate that this differentiation possibly derived from physiological differences related to phylogeny, and was not affected by reproductive or environmental seasonality.

scholarly journals Geographic variation in adult and embryonic desiccation tolerance in a terrestrial-breeding frog

2018 ◽  
Author(s):  
T.S. Rudin-Bitterli ◽  
J.P. Evans ◽  
N.J. Mitchell
Keyword(s):  
Climate Change ◽  
Geographic Variation ◽  
Desiccation Tolerance ◽  
Swimming Performance ◽  
Clinal Variation ◽  
Rainfall Gradient ◽  
Change Models ◽  
Environmental Perturbations ◽  
Specific Variation ◽  
Almost All

ABSTRACTIntra-specific variation in the ability of individuals to tolerate environmental perturbations is often neglected when considering the impacts of climate change. Yet this information is potentially crucial for mitigating any deleterious effects of climate change on threatened species. Here we assessed patterns of intra-specific variation in desiccation tolerance in the frogPseudophryne guentheri, a terrestrial-breeding species experiencing a drying climate. Adult frogs were collected from six populations across a rainfall gradient and their dehydration and rehydration rates were assessed. We also compared desiccation tolerance of embryos and hatchlings originating from within-population parental crosses from four of the six populations, where selection on desiccation tolerance should be especially strong given that embryos cannot move to escape unfavourable microclimates. Embryos were reared on soil at three soil-water potentials, ranging from wet to dry (ψ = −10, −100 & −400 kPa), and their desiccation tolerance was assessed across a range of traits including survival, time to hatch after inundation, wet mass at hatching, hatchling malformations and swimming performance. We found significant and strong patterns of intra-specific variation in almost all traits, both in adults and first generation offspring. Adult frogs exhibited clinal variation in their water balance responses, with populations from drier sites both dehydrating and rehydrating more slowly compared to frogs from more mesic sites. Similarly, desiccation tolerance of embryos and hatchlings was significantly greater in populations from xeric sites. Taken together, our findings suggest that populations within this species will respond differently to the regional reduction in rainfall predicted by climate change models. We emphasise the importance of considering geographic variation in phenotypic plasticity when predicting how species will respond to climate change.

Intra- and inter-specific variation in pupation behaviours of Drosophila from different habitats

1990 ◽  
Vol 68 (12) ◽  
pp. 2616-2619
Author(s):  
Lucy Rodriguez ◽  
Marla B. Sokolowski ◽  
Yves Carton
Keyword(s):  
Drosophila Melanogaster ◽  
Intraspecific Variation ◽  
Habitat Type ◽  
Strain Variation ◽  
Collection Site ◽  
Laboratory Rearing ◽  
Interspecific Differences ◽  
Pupation Height ◽  
Specific Variation ◽  
Isofemale Strains

Isofemale strains of Drosophila melanogaster and D. simulans were collected from wet and dry habitats in Tunisia. These strains were used to study the effect of habitat (collection site) and laboratory rearing temperature on larval pupation behaviour of these species. Results showed that D. melanogaster isofemale strains from the wet habitat pupated significantly higher in vials than those from the drier habitat. In contrast, the pupation behaviour of D. simulans isofemale strains was not affected by habitat type. Significant intraspecific variation in pupation behaviour was found for both species from both habitats. The distance pupated away from food in vials was positively correlated to the distance pupated from fruit in a field-like assay. Plasticity for pupation height was found at 16 and 32 °C for both species. Greater between-strain variation in pupation height was found for D. melanogaster at 32 °C and for D. simulans at 16 °C. The patterns of interspecific differences in larval pupation height paralleled those previously reported for adult behaviour patterns in these species.

Habitat Association of Klebsiella Species

1985 ◽  
Vol 6 (2) ◽  
pp. 52-58 ◽  
Author(s):  
Susan T. Bagley
Keyword(s):  
Drinking Water ◽  
Gastrointestinal Tract ◽  
Surface Waters ◽  
Industrial Effluents ◽  
Opportunistic Pathogen ◽  
Habitat Associations ◽  
Habitat Association ◽  
Klebsiella Species ◽  
Almost All ◽  
Polluted Waters

AbstractThe genus Klebsiella is seemingly ubiquitous in terms of its habitat associations. Klebsiella is a common opportunistic pathogen for humans and other animals, as well as being resident or transient flora (particularly in the gastrointestinal tract). Other habitats include sewage, drinking water, soils, surface waters, industrial effluents, and vegetation. Until recently, almost all these Klebsiella have been identified as one species, ie, K. pneumoniae. However, phenotypic and genotypic studies have shown that “K. pneumoniae” actually consists of at least four species, all with distinct characteristics and habitats. General habitat associations of Klebsiella species are as follows: K. pneumoniae—humans, animals, sewage, and polluted waters and soils; K. oxytoca—frequent association with most habitats; K. terrigena— unpolluted surface waters and soils, drinking water, and vegetation; K. planticola—sewage, polluted surface waters, soils, and vegetation; and K. ozaenae/K. rhinoscleromatis—infrequently detected (primarily with humans).

SEM Cold Stage Techniques for the Observation of Vegetative and Floral Apices of Oat (Avena sativa L.) Plants

1977 ◽  
Vol 35 ◽  
pp. 590-591
Author(s):  
B. K. Kirchoff ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Critical Point ◽  
Avena Sativa ◽  
Substantial Improvement ◽  
Fresh Tissue ◽  
Cold Stage ◽  
Critical Point Drying ◽  
Almost All ◽  
Cell Collapse ◽  
Conductive Paint ◽  
Carbon Based

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.

Electron microscopy studies of plasma-sprayed materials

1983 ◽  
Vol 41 ◽  
pp. 70-71
Author(s):  
K.R. Subramanian ◽  
A.H. King ◽  
H. Herman
Keyword(s):  
Plasma Spraying ◽  
Substrate Surface ◽  
Flame Temperature ◽  
Ceramic Coatings ◽  
Metallic Substrates ◽  
Hot Plasma ◽  
Almost All ◽  
Plasma Sprayed ◽  
Hostile Environments ◽  
Plasma Spraying Process

Plasma spraying is a technique which is used to apply coatings to metallic substrates for a variety of purposes, including hardfacing, corrosion resistance and thermal barrier applications. Almost all of the applications of this somewhat esoteric fabrication technique involve materials in hostile environments and the integrity of the coatings is of paramount importance: the effects of process variables on such properties as adhesive strength, cohesive strength and hardness of the substrate/coating system, however, are poorly understood.Briefly, the plasma spraying process involves forming a hot plasma jet with a maximum flame temperature of approximately 20,000K and a gas velocity of about 40m/s. Into this jet the coating material is injected, in powder form, so it is heated and projected at the substrate surface. Relatively thick metallic or ceramic coatings may be speedily built up using this technique.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

Quantitative Freeze Fracture Studies of Gap Junctions in Somatic Cell Hybrids, Their Parents, and Revertants

1976 ◽  
Vol 34 ◽  
pp. 218-219
Author(s):  
W. J. Larsen ◽  
R. Azarnia ◽  
W. R. Loewenstein
Keyword(s):  
Gap Junctions ◽  
Striated Muscle ◽  
Freeze Fracture ◽  
Cell Movement ◽  
Dye Molecules ◽  
Somatic Cell Hybrids ◽  
Cell Coupling ◽  
Normal Cells ◽  
Mediate Cell ◽  
Almost All

Although the physiological significance of the gap junction remains unspecified, these membrane specializations are now recognized as common to almost all normal cells (excluding adult striated muscle and some nerve cells) and are found in organisms ranging from the coelenterates to man. Since it appears likely that these structures mediate the cell-to-cell movement of ions and small dye molecules in some electrical tissues, we undertook this study with the objective of determining whether gap junctions in inexcitable tissues also mediate cell-to-cell coupling.To test this hypothesis, a coupling, human Lesh-Nyhan (LN) cell was fused with a non-coupling, mouse cl-1D cell, and the hybrids, revertants, and parental cells were analysed for coupling with respect both to ions and fluorescein and for membrane junctions with the freeze fracture technique.

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